Physical-chemical characterisation of an alum-based water treatment sludge in different raw water turbidity scenarios.

Characterisation of the water treatment sludge (WTS) generated in drinking water treatment plants (DWTPs) is crucial to define alternatives for its adequate management, including potential reuse options. To define these alternatives, it is necessary to evaluate rainfall seasonality effect on WTS production and its physical and chemical characteristics. This study assessed the production and characterisation of four types of alum-based WTS. The WTS was generated in a pilot-scale system from different raw water turbidities (i.e., low: <5 NTU, medium: 5-10 NTU, high: ≥10 NTU, and very high turbidity: ∼300 NTU) and coagulant doses. To estimate WTS production, mathematical models based on variables such as raw water turbidity, coagulant dosage, and organic matter removed were used. The WTS characterisations included physical (solids and particle size distribution), chemical (metallic oxides, pH, mineral phases), and surface properties (functional groups and zero-charge point pH). The modified Kawamura model presented the best fit (R2 = 1.0, RMSE = 0.1062 and the lower Akaike Information Criterion) for the estimation of WTS production, indicating that at the DWTPs, it is possible to make sludge production projections using only two simple variables: coagulant dose and the raw water turbidity. The four types of WTS consist mainly of amorphous materials (45-65 %), featuring some mineral phases and exhibiting high contents of Al (Al2O3: 30-34 %), Si (SiO2: 21-26 %) and Fe (Fe2O3: 11-13 %). Nevertheless, very high turbidity WTS shows variations in its characteristics, notably a heightened content of clays. As a result of the high concentrations of Al and Fe, the WTS has the potential to be used as coagulants or for the recovery of coagulants, especially low turbidity WTS, which is produced from water with low turbidity and organic matter. The presence of aluminium-silicate clays and the surface functional groups of the silica network suggest that WTS, particularly very high turbidity WTS, also has the potential to be raw materials for generating adsorbents. The potential applications of WTS in coagulation and adsorption can be leveraged in wastewater treatment, promoting the circular economy in the water sector.

Coupling coordination between electricity and economy: China as an example.

The benign coupling coordination between electricity (EL) and economy (EC) contributes to a better environment and sustainability. This study explores whether EL and EC can coordinate theoretically, how to evaluate their coordination, what the statuses are, and how to enhance coupling coordination levels (CCL). Specifically, we select the data from 2011 to 2020 of the 31 provincial regions of China, use information entropy weight and the technique for order preference by similarity to an ideal solution method, establish the theoretical coupling coordination mechanism and the evaluation index system to measure CCL temporally-spatially and propose policy implications based on prediction tendencies. We find that most regions' CCLs fluctuate temporally with mild upward trends, indicating the much more benign coupling coordination status; the spatial distributions are uneven with narrowing gaps. However, future CCL gaps may increase; therefore, differentiated policy implications are needed, such as encouraging balanced-coordination policies, innovating for higher-quality coordination, and cooperating for intelligence and wealth transfer. This study is conducive to theoretically describing the coupling coordination mechanism between EL and EC, providing new insights for CCL evaluation and the coordination practice for different regions.

Exploring the potential of Hermetia illucens larvae extracts: A promising approach for dermocosmetic formulations.

Globally, the yearly disposal of 1.3 billion tonnes of food raises environmental and public health concerns. Black soldier fly (BSF) larvae present a sustainable solution, converting organic waste into nutrient-rich biomass. The extracted oil from BSF larvae, rich in fatty acids (FA), offers an eco-friendly alternative for the cosmetic industry. In this study, larvae sourced from a Portuguese company were fed olive pomace, a by-product of olive oil production. The lipidic sample extracted revealed a composition high in oleic acid, valuable for cosmetics. Investigating the biological activity of lipid extractions from larvae fed with olive pomace is a novel approach. Notably, the n-hexane ultrasound-assisted extraction method demonstrated potent antioxidant properties, and some extracts displayed antimicrobial activity. Five non-cytotoxic extracts; three with no relevant activity (IC50 from 236 to >400 µg/mL). These findings highlight BSF larvae as an environmentally friendly source of fatty acids, offering promising alternatives for diverse applications.

Recent evolution in thermochemical transformation of municipal solid wastes to alternate fuels.

The management of solid waste poses a worldwide obstacle in the pursuit of a sustainable society. This issue has intensified with the increase in waste production caused by rapid population expansion, industrialization, and urbanization. The continuously growing volume of municipal solid waste, particularly the substantial volume of organic waste, along with improper disposal practices, results in the release of greenhouse gases and other harmful airborne substances which simultaneously causes health risks and socioeconomic concerns. This article examines various waste-to-energy (energy production in the form of heat and electricity) concepts as well as waste-to-materials (various value-added materials including biofuel, biochemical, char, bio-oil, soil fertilizer, etc.) methods of converting municipal solid waste into environmentally friendly fuels, which appear to be economically feasible and attractive. It starts with a thorough analysis of the characteristics of municipal solid waste followed by the generation procedure. The study provides an overview of different thermochemical conversion methods including incineration, pyrolysis, co-pyrolysis, liquefaction, hydrothermal carbonization, gasification, combustion for transformation of municipal solid waste, and their recent advancement. The review comprehensively discussed the pros and cons of each method highlighting their strength, weakness, opportunities, and threats to transforming MSW. The current state of municipal solid waste management, including effective dumping and deviation, is comprehensively assessed, along with the prospects and challenges involved. Energy justice concepts and fuzzy logic tool is used to address the selection criteria for choosing the best waste treatment techniques. Moreover, several recommendations are offered to enhance the existing solid waste management system. This review could assist scholars, researchers, authorities, and stakeholders in making informed decisions regarding MSW management.

Catalysing Environmental Action: a Governance Framework for Enhancing Individual Participation in Sub-Saharan Africa's Plastic Circular Economy.

Plastic waste poses a significant challenge to achieving sustainable production and consumption of resources, particularly in sub-Saharan Africa where effective governance and waste management systems are lacking. In this paper, we develop an empirical understanding of the influence of public governance system on promoting circular economy (CE) for plastic actions among individuals. Through a survey of 1475 participants across five sub-Saharan African countries, we tested five hypotheses drawing on New Governance Theory and CE Action Recipe to explore the relationship between governance and individual's actions supporting CE for plastic. We found that a governance system that supports CE practices and exhibits governance efficiency is positively associated with individuals' actions supporting CE for plastic. The awareness of government policies, laws and regulations, institutions, processes, and programmes have a significant impact on individuals' engagement in plastic circularity practices. The paper's theoretical and governance implications highlight the relevance of public governance in shaping action towards a CE for plastic at the individual level.

Circular economy, economic growth, and e-waste generation in EU27 countries: Further evidence from the novel circular economy index and threshold effect.

The circular economy has been identified as a critical keyword for achieving the Sustainable Development Goals. Nevertheless, there is a lack of in-depth empirical literature on the impact mechanisms of the circular economy (CE) and economic growth (GDP) in mitigating e-waste generation (waste electrical and electronic equipment - WEEE). Given Europe's leading position in e-waste generation per capita, the study aims to scrutinize the interplay between CE, GDP, and WEEE for 2010-2020. The research applies advanced econometric methods, primarily centered around the system generalized method of moment and dynamic panel threshold. It was noteworthy that different CE indicators exhibited varying effects on WEEE through the econometric analysis. Therefore, the research uniquely utilized the entropy weight method to compute a holistic composite index for the circular economy (CEI) and gained some interesting findings. Firstly, CEI significantly reduced WEEE, while GDP drove its increase. However, an overly developed CEI of 0.7616 counteracted its beneficial effect. Secondly, the synergy of CEI*GDP engendered the circular economy rebound effect, diminishing environmental benefits. Thirdly, in the circular context, the environmental Kuznets curve was validated, showcasing an inverted U-shaped pattern. Finally, the study found CEI to have different threshold effects, with thresholds of 0.2161 to inhibit WEEE, 0.2114 to avert the circular economy rebound effect, and 0.2360 to leverage GDP in reducing WEEE. These outcomes give insights to policymakers in designing sound policies targeting circular economy development and decoupling e-waste generation from economic growth towards the United Nations' SDGs.

Improving the re-use potential of reactive waste rock using sieving: a laboratory geochemical study.

Stockpiles containing sulfide minerals are subject to oxidation reactions when exposed to atmospheric conditions, which can result in the formation of acid mine drainage (AMD). Reactive waste rock has limited re-use potential due to the contamination risk associated with the generated drainage water. The re-use of reactive waste rock could lead to a significant reduction in the volume of waste rock as it mitigates the environmental impact of mine waste deposition. Acid mine drainage generation rate depends on sulfide weathering kinetics which are controlled by many parameters such as the mineralogy and the particle size. Fine fractions of waste rock have higher specific surface areas and degree of liberation of sulfides, resulting in greater reactivity than the coarse fractions. The objective of this research was therefore to evaluate the potential of re-use by controlling particle size using the sieving method. Two different potentially acid-generating waste rocks were divided into six fractions and subjected to both static and kinetic tests. Prediction of the geochemical behavior using static test did not consider the liberation of the minerals, and the long-term prediction was therefore overestimated. Results of the kinetic columns showed there was less oxidation of the sulfide minerals in the coarse fractions than in the fine fractions. Additionally, the distribution of sulfidic minerals and neutralizing minerals with particle size is influencing the potential of the re-use of the reactive waste rock.

Contributions of heterogeneous catalysis enabling resource efficiency and circular economy.

Our industry today is predominantly based on linear value chains. Raw materials are extracted from primary sources, processed into products, used, and disposed of at the end of their life cycle. This linear economy causes a wide range of negative environmental impacts owing to the resulting greenhouse gas emissions and pollution of marine and terrestrial ecosystems. Closed carbon cycles and climate-neutral energy production are essential for the production not only of fuels but also of all chemicals, including plastics and fertilizers, to counteract climate change and further damage to the environment. In this regard, this article discusses the importance of heterogeneous catalysts for selected technologies associated with this transformation of the resource base and energy supply. It discusses the technological framework conditions of a net CO2-neutral industry, with a focus on electrocatalytic water-splitting for hydrogen production, as well as the catalytic challenges of production of chemicals for the whole value chain using biomass, CO2 and plastic waste as raw materials. This article is part of the discussion meeting issue 'Green carbon for the chemical industry of the future'.

Green carbon and the chemical industry of the future.

The pressing need to mitigate climate change and drastically reduce environmental pollution and loss of biodiversity has precipitated a so-called energy transition aimed at the decarbonization of energy and defossilization of the chemical industry. The goal is a carbon-neutral (net-zero) society driven by sustainable energy and a circular bio-based economy relying on renewable biomass as the raw material. It will involve the use of green carbon, defined as carbon derived from terrestrial or aquatic biomass or organic waste, including carbon dioxide and methane emissions. It will also necessitate the accompanying use of green hydrogen that is generated by electrolysis of water using a sustainable source of energy, e.g. solar, wind or nuclear. Ninety per cent of the industrial chemicals produced in oil refineries are industrial monomers that constitute the precursors of a large variety of polymers, many of which are plastics. Primary examples of the latter are polyolefins such as polyethylene, polypropylene, polyvinyl chloride and polystyrene. Polyolefins are extremely difficult to recycle back to the olefin monomers and discarded polyolefin plastics generally end up as the plastic waste that is responsible for the degradation of our natural habitat. By contrast, waste biomass, such as the lignocellulose contained in forestry residues and agricultural waste, constitutes a renewable feedstock for the sustainable production of industrial monomers and the corresponding polymers. The latter could be the same polyolefins that are currently produced in oil refineries but a more attractive long-term alternative is to produce polyesters and polyamides that can be recycled back to the original monomers: a paradigm shift to a truly bio-based circular economy on the road to a net-zero chemical industry. This article is part of the discussion meeting issue 'Green carbon for the chemical industry of the future'.

Towards a unified carbon accounting landscape.

The overarching purpose of carbon accounting is to reduce carbon emissions to meet net-zero targets and minimize the impact of climate change. However, the plethora of methods and approaches used means that products and systems sometimes cannot easily be compared. The mix of regional and life cycle-based systems can mean that we lack global oversight of our emissions and impact. In some situations where a regional approach is used, industry/business/regions are incentivized to reduce their own/territorial emissions, which can mean that an optimal global solution is not adopted. Countries where grid emissions are higher can be selected for production because it reduces regional (not global) carbon levels. Furthermore, these can be areas where the climate impact may be felt the most: not the just transition we aspire to. Our work provides an analysis of the current system together with its challenges and limitations, paving the way towards a more unified framework to create climate justice together with transparent and comparable accounting methodology for industry and regions alike. This article is part of the discussion meeting issue 'Green carbon for the chemical industry of the future'.

Sustainable valorization of waste plastic into nanostructured materials for environmental, energy, catalytic and biomedical applications: A review.

The extensive production and utilization of plastic products are inevitable in the current scenario. However, the non-degradable nature of waste plastic generated after use poses a grave concern. Comprehensive efforts are being made to find viable technological solutions to manage the escalating challenge of waste plastic. This review focuses on the progress made in transformation of waste plastic into value-added nanomaterials. An overview is provided of the waste plastic issue on a global level and its ecological impacts. Currently established methodologies for waste plastic management are examined, along with their limitations. Subsequently, state-of-the-art techniques for converting waste plastic into nanostructured materials are presented, with a critical evaluation of their distinct merits and demerits. Several demonstrated technologies and case studies are discussed regarding the utilization of these nanomaterials in diverse applications, including environmental remediation, energy production and storage, catalytic processes, sensors, drug delivery, bioimaging, regenerative medicine and advanced packaging materials. Moreover, challenges and prospects in the commercial level production of waste plastic-derived nanomaterials and their adoption for industrial and practical usage are highlighted. Overall, this work underscores the potential of transforming waste plastic into nanostructured materials for multifaceted applications. The valorization approach presented here offers an integration of waste plastic management and sustainable nanotechnology. The development of such technologies should pave the way toward a circular economy and the attainment of sustainable development goals.

Impact of the circular economy on ecological footprint: evidence from Germany.

The circular economy practices contribute to sustainable development by maximising efficiency, utilising renewable resources, extending product lifespans, and implementing waste reduction strategies. This study investigates the individual impacts of four sources of the circular economy on the ecological footprint in Germany, a country that is among the pioneers in establishing a comprehensive roadmap for the circular economy. The four sources examined are renewable energy consumption (REC), recycling, reuse, and repair of materials. Using time series data from 1990 to 2021, the study employed the dynamic autoregressive distributed lag (ARDL) simulation technique and also applied kernel-based linear regression (KRLS) to test the robustness of the results. The findings revealed that reuse practices significantly reduce the ecological footprint in both the short and long run. REC and repair also substantially decrease the ecological footprint, as shown by the simulation analysis. Conversely, while recycling is generally considered crucial for minimising environmental impact, in this study, it was found to contribute to environmental degradation. This paradox may be attributed to the nascent state of the recycling industry and data limitations. The results from KRLS confirm the findings of the dynamic ARDL. It is recommended that policymakers develop measures that are appropriate, efficient, and targeted to enhance the role of each source of the circular economy in reducing the ecological footprint in Germany. The major limitation of the study is its reliance on the indirect measures of circular economy attributed to the non-availability of data on direct measures.

The Influence of Barley Proteome on Hop Bitter Acid Yield during Brewing.

A persistent challenge in brewing is the efficient utilization of hop bitter acids, with about 50% of these compounds precipitating with trub during wort boiling. This study aims to uncover the correlation between the barley cultivar proteome and hop bitter acid utilization during wort boiling. Therefore, comparative experiments were conducted using two cultivars, Liga and Solist, with varying proteomes to identify specific proteins' role in hop bitter acids precipitation. High-performance liquid chromatography (HPLC) was used to measure hop bitter acid content, while liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to quantify and identify proteins. The 107 protein groups, particularly enzymes linked to barley metabolic defense mechanisms, exhibited significant differences between the two cultivars. Results revealed significantly lower α- and iso-α-acid content in wort produced from the barley cultivar Liga. This study highlights the critical role of the barley proteome in optimizing process efficiency by enhancing hop utilization through barley cultivar selection.

Barriers and framework conditions for the market entry of second-life lithium-ion batteries from electric vehicles.

Transition to circular economy for lithium-ion batteries used in electric vehicles requires integrating multiple stages of the value cycle. However, strategies aimed at extending the lifetime of batteries are not yet sufficiently considered within the European battery industry, particularly regarding repurposing. Using second-life lithium-ion batteries (SLBs) before subsequent recycling can offer several advantages, such as the development of sustainable business models, the reduction of emissions, and alignment with UN Sustainable Development Goals 7, 12, and 13. Using expert and problem-centred interviews along with an exploratory workshop, this study guides stakeholders in the battery sector by illustrating the necessary changes for a more holistic circular economy. Moreover, an extended political, economic, social, technological, environmental, legal, and additionally safety-related (PESSTEL) analysis approach is carried out, which has not yet been used in this context. In this process, barriers, as well as necessary institutional framework conditions and organisational requirements for a successful market entry of SLB applications are investigated. Among others, key barriers relate to the competition with first-life applications and safety concerns. SLBs require high manual labour costs for repurposing, along with expenses for expired warranties and re-certifications. Ownership structures in traditional business models often result in SLBs and their corresponding usage data staying under the control of the manufacturers. Market viability, however, requires a level playing field for both first-life and second-life operators as well as circular battery and data-sharing business models. Gathering data on the ageing performance and performing improved safety testing according to test protocols facilitates the reliable assessment of SLBs.

Enhancing circular plastic waste management: Reducing GHG emissions and increasing economic value in Rayong province, Thailand.

This study evaluates the greenhouse gas (GHG) emissions and economic value creation of plastic waste (PW) management in Rayong, Thailand, a city on the eastern Gulf Coast with a significant amount of generated and leaked PW. By analyzing current practices, and developing and evaluating improvement scenarios, the study explores strategies for reducing GHG and enhancing economic benefits across the PW management chain. Four primary routes with varying capacities handle approximately 5,445.55 tonnes of PW via source separation recycling (5.18 %), post-sorting recycling (9.30 %), energy recovery (54.86 %), and landfills or opened dump disposal (30.66 %). About 83.21 % of the 16 ± 6.9 % PW in municipal solid waste (MSW) is recyclable, primarily consisting of high-density polyethylene (HDPE), polypropylene (PP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polyethylene terephthalate (PET). The current management practice generates an economic benefit of approximately 1.68 million USD/yr or 310 USD/t of PW, compared to the proposed scenarios, which enhances recycling efficiency and reduces landfill and energy recovery waste, yielding 2.27-6.48 million USD/yr or 420.64-1200.33 USD/t of PW. The practice emits about 7,028.47 tCO2e annually, while improved source and post-sorting efficiencies reduce GHG emissions by 2.86-3.17 times or -2.83 to -2.42 tCO2e/t of PW or a total of over 13,078.60-15,268.44 tCO2e. Burning PW increases approximately 1.6 times or 11,841.36 tCO2e/yr. Enhancing recycling efficiency, particularly through source separation, is key to promoting more productive and valuable PW separation, increasing economic value and GHG mitigation by approximately 3.87 and 3.17 times, respectively. These findings provide valuable insights for local authorities and policymakers to develop strategic interventions and policies that align with the improved scenario by enhancing source separation and recycling. The results demonstrate that improving the efficiency of separation at the source is critical for transitioning from a linear PW management strategy to a circular economy, significantly reducing landfill waste and mitigating environmental threats.

Tamarillo (Solanum betaceum Cav.) wastes and by-products: Bioactive composition and health benefits.

Introduction: During processing, a large amount of by-products is produced from tamarillo fruits in the form of stalks, outer skins, and pomace (residual seeds and inner skins). This material is a renewable source of bioactive compounds with high economic value and positive effects on human health. Previous reviews have focused on the ethnobotanical, traditional uses, and phytochemistry of the tamarillo fruit. This report aims to compile production and cultivation data, as well as the valorization of this agro-industrial residue, green extraction methods used for extracting the bioactive compounds, and their biological activity. Method: In this study, a literature search was conducted in five scientific databases: Web of Science, ScienceDirect, Scopus, PubMed, and Google Scholar to retrieve research published in English, Spanish, or Portuguese between 2009 and 2024, which mentions the composition and extraction methods of bioactive compounds from tamarillo wastes and by-products and the health benefits associated with these compounds. The data extracted was compiled and shown in this scoping review. Results: Tamarillo wastes and by products have a rich nutritional and bioactive composition, including high protein, vitamins A and C, minerals, dietary fiber, sugars, terpenes, flavonoids, carotenoids, anthocyanins, and other phytochemicals. Green methods have been effective, yielding high amounts of these compounds while preserving their integrity. Natural polyphenols have shown antioxidant, anticholinesterase, anti-inflammatory, antimicrobial, anti-diabetic, and anti-obesity properties. The antioxidant fibers, mucilage, and pectin of the pomace contribute to improved intestinal health. Conclusion: Therefore, these wastes and by-products have potential uses as natural colorant, antioxidants, supplements, functional foods, active biobased films, and in pharmaceutical and cosmeceutical sectors due to their effective bioactive molecules. Future research should focus on the use of tamarillo by-products as a source of functional ingredients in several other formulations that are still little explored, as well as their use as a natural colorant and antioxidant. More studies are necessary on the composition-activity relationship, physiological mechanisms, and clinical response.

Carbon dioxide as a sustainable reagent in circular hydrometallurgy.

This review highlights the use of CO2 as a reagent in hydrometallurgy, with emphasis on the new concept of circular hydrometallurgy. It is shown how waste CO2 can be utilised in hydrometallurgical operations for pH control or regeneration of acids for leaching. Metal-rich raffinate solutions generated after removal of the valuable metals can serve as feedstocks for mineral carbonation, providing alternative avenues for CO2 sequestration. Furthermore, CO2 can also be used as a renewable feedstock for the production of chemical reagents that can find applications in hydrometallurgy as lixiviant, as precipitation reagent or for pH control. Mineral carbonation can be combined with chemical reactions involving metal complexation reagents, as well as with solvent extraction processes for the concurrent precipitation of metal carbonates and acid regeneration. An outlook for future research in the area is also presented.

Establishment of circular economy by utilising textile industry waste as an adsorbent for textile dye removal.

This study explored the use of waste from the textile industry (silkworm byproducts) as a promising raw feedstock for the production of carbon-based adsorbents (biochar). The silk excreta biochar generated at 600 and 700 °C (referred to as SEB-600 and SEB-700, respectively) were evaluated in terms of their efficacy in adsorbing cationic (methylene blue) and anionic (Congo red) textile dyes. Although the functional groups on the surfaces of SEB-600 and SEB-700 were not significantly different, the specific surface area of SEB-700 was greater than that of SEB-600. The dye adsorption capacity of SEB-700 was higher than that of SEB-600. The adsorption of methylene blue and Congo red on SEB-700 followed Freundlich isotherms (R2 ≥ 0.963) and pseudo-second-order kinetics (R2 = 0.999), indicating chemisorption with multilayer characteristics. The mechanism for the adsorption of methylene blue on SEB-700 may involve interactions with the negatively charged functional groups on the surface and the mesopores of SEB-700. For the adsorption of Congo red, the mesopores in the biochar and the electrostatic interaction between biochar (positively charged because of the dye solution pH < pHzpc) and the anionic dye could affect adsorption. The maximum adsorption capacities of SEB-700 for methylene blue and Congo red were determined to be 168.23 and 185.32 mg g-1, respectively. Utilising the waste generated from the textile industry to remove pollutants will build a sustainable loop in the industry by minimising waste generation and pollutant emissions.

The potential of insect frass for sustainable biogas and biomethane production: A review.

Insect-based protein production has gained traction in recent years. This has led to the increasing production of frass, the residual substrate from insect farming. As a relatively new substrate with characteristics that are not widely known, its energetic potential still needs to be investigated. In this context, this literature review aims to evaluate the potential of frass as a feedstock for bioenergy production through anaerobic digestion. From the literature search, 11 studies were selected, and showed a wide range of biogas (44 m3/ton VS to 668 m3/ton VS) and methane (26 m3/ton VS to 502 m3/ton VS) production potentials from insect frass, mostly comparable with traditional biomasses of liquid and solid slurry. Results are influenced by factors such as substrate type, digestion conditions and presence of co-digestion substrates. The need of further investigation on the economic viability has been highlighted, with a focus on the possibility of upgrading biogas to vehicle-grade biomethane.